Methods utilizing microwave radiation during formation of semiconductor constructions

ABSTRACT

Some embodiments include methods in which microwave radiation is used to activate dopant and/or increase crystallinity of semiconductor material during formation of a semiconductor construction. In some embodiments, the microwave radiation has a frequency of about 5.8 gigahertz, and a temperature of the semiconductor construction does not exceed about 500° C. during the exposure to the microwave radiation.

RELATED PATENT DATA

This patent resulted from a continuation of U.S. patent application Ser.No. 12/208,886, which was filed Sep. 11, 2008, and which is herebyincorporated herein by reference.

TECHNICAL FIELD

Methods utilizing microwave radiation during formation of semiconductorconstructions.

BACKGROUND

Semiconductor device fabrication is utilized to form integratedcircuitry (IC), micro-electro-mechanical systems (MEMS), and othermicro-structures and assemblies.

The fabrication of an IC may involve implanting dopant into asemiconductor substrate, followed by activation of the dopant.

The implanting may comprise directing energized atoms or molecules ofdopant at a semiconductor substrate to drive the dopant to a desireddepth within the substrate, and may damage the substrate. For instance,if the dopant is driven into a monocrystalline silicon substrate, someregions of the substrate may become amorphous due to interaction of suchregions with the energized atoms or molecules of the dopant.

The amorphous regions are defects, and may disrupt operation ofintegrated circuit components. Accordingly, it is desired torecrystallize the amorphous regions. Thermal energy has been used torecrystallize amorphous regions. However, many materials utilized in ICare not stable to the thermal energy utilized for recrystallization ofsilicon. If such materials are present, thermal energy cannot be usedfor recrystallization of the amorphous silicon without taking a risk ofdamage to the thermally unstable materials. It is therefore desired todevelop new methods for recrystallizing amorphous regions.

Amorphous regions may occur through other mechanisms besides as defectsinduced during a dopant implant, and may be problematic in otherstructures besides integrated circuits. For instance, amorphous regionsmay be problematic in MEMS, and accordingly it would be desired todevelop methods that may be applied to diverse applications ofsemiconductor device fabrication, including, but not limited to MEMsfabrication and IC fabrication.

Some improved methods have been developed for recrystallization ofamorphous regions, with such improved methods comprising exposure of asemiconductor construction to radiofrequency radiation or to microwaveradiation. However, even the improved methods may lead to undesiredheating of semiconductor constructions, and accordingly it would bedesired to develop new methods for recrystallization of amorphousregions.

As mentioned above, dopant is activated after it is implanted into asemiconductor substrate. The activation of the dopant comprisestransferring the dopant from interstitial positions adjacent a latticestructure of a semiconductor material, into lattice sites of the latticestructure. Dopant activation is traditionally done utilizing thermalenergy, but such may lead to the same problems that were describedpreviously as being associated with the utilization of thermal energyfor recrystallization of amorphous material. There has been some effortto utilize radiofrequency radiation or microwave radiation for dopantactivation, but such may still lead to undesired heating of thesemiconductor construction. It is therefore desired to develop methodsfor activating dopant which avoid undesired heating of semiconductorconstructions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-3 are diagrammatic, cross-sectional views of a portion of asemiconductor construction at various process stages of an exampleembodiment.

FIGS. 4 and 5 are diagrammatic, cross-sectional views of a portion of asemiconductor construction at various process stages of an exampleembodiment.

FIGS. 6-9 are diagrammatic, cross-sectional views of a portion of asemiconductor construction at various process stages of an exampleembodiment.

FIGS. 10 and 11 are diagrammatic, cross-sectional views of a portion ofa semiconductor construction at various process stages of an exampleembodiment.

FIG. 12 is a diagrammatic, cross-sectional view of a portion of asemiconductor construction at a process stage of an example embodiment.

FIG. 13 is a diagrammatic, cross-sectional view of a portion of asemiconductor construction at a process stage of an example embodiment.

FIG. 14 is a diagrammatic view of a computer embodiment.

FIG. 15 is a block diagram showing particular features of themotherboard of the FIG. 14 computer embodiment.

FIG. 16 is a high level block diagram of an electronic systemembodiment.

FIG. 17 is a simplified block diagram of a memory device embodiment.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Some embodiments comprise utilization of microwave radiation having afrequency of about 5.8 gigahertz to activate dopant within asemiconductor construction and/or to induce crystallization ofsemiconductor material. The microwave radiation is referred to as havinga frequency of “about” 5.8 gigahertz to indicate that there willgenerally be some spectrum of radiation having the bulk energy at thefrequency of 5.8 gigahertz. The frequency of 5.8 gigahertz correspondsto a wavelength of about 5.2 centimeters, and the radiation may bealternatively referred to as having a main spectrum wavelength peak atabout 5.2 centimeters.

Microwave radiation having a frequency of about 5.8 gigahertz coupleswith silicon of silicon-containing semiconductor constructions, but doesnot couple with metals, metal-containing compositions, and electricallyinsulative compositions that may be comprised by the semiconductorconstructions. The term “couple” is utilized to indicate that energy istransferred from the microwave radiation to an indicated material, andthe term “decouple” is used to indicate that the microwave radiationdoes not transfer energy to the indicated material.

Microwave radiation having a frequency of about 5.8 gigahertz is foundto couple with silicon at low temperatures, and to decouple at highertemperatures. The coupling may only occur at temperatures less than orequal to 500° C., in some embodiments may only occur at temperaturesless than or equal to 400° C., and in some embodiments may only occur attemperatures of less than or equal to about 350° C. The temperature atwhich the silicon transitions from coupling with the microwave radiationto being decoupled from the microwave radiation may be referred to as adecoupling temperature. The temperatures refer to a bulk isothermalstate.

If the microwave radiation couples with the silicon, the microwaveradiation may induce activation of dopant within such silicon and/orinduce crystallization of such silicon. In contrast, the silicon abovethe decoupling temperature is transparent to the microwave radiation,and accordingly the microwave radiation does not impart energy tosilicon that is above the decoupling temperature.

The decoupling may be considered to be thermally-induced decoupling, inthat the decoupling is induced by a change in temperature of the siliconmaterial. Such thermally-induced decoupling may be taken advantage ofduring fabrication of semiconductor constructions to avoid heating ofthe constructions to temperatures that would cause problems withthermally unstable materials.

For instance, some metal silicides are thermally unstable, andconventional fabrication of semiconductor constructions would notattempt activation of dopant and/or recrystallization of semiconductormaterial after formation of such metal silicides. This causes difficultyin designing fabrication processes, because there are times when itwould be desired to utilize such metal silicides, and yet the metalsilicides would be formed prior to the implant of a dopant that wouldsubsequently need to be activated. Generally, such difficulties areaddressed by utilizing less desired conductive compositions instead ofthe desired metal silicide. However, the decoupling mechanism discussedabove enables microwave radiation of 5.8 gigahertz to be utilized toactivate dopant regardless of whether a thermally-unstable metalsilicide is present.

As another example, phase change materials are often thermally unstable,and conventional fabrication of semiconductor constructions would notattempt activation of dopant and/or recrystallization of semiconductormaterial after formation of phase change materials. This causesdifficulty in designing fabrication processes, because there are timeswhen it would be desired to utilize phase change materials, and yet thephase change materials would be formed prior to the implant of a dopantthat would subsequently need to be activated. However, the decouplingmechanism discussed above enables microwave radiation of 5.8 gigahertzto be utilized to activate dopant regardless of whetherthermally-unstable phase change materials are present.

Other advantages of the utilization of 5.8 gigahertz radiation toactivate dopant in silicon is that the activation is self-limiting, andthe 5.8 gigahertz radiation induces little or no diffusion of dopantwithin a silicon matrix. Accordingly, if the 5.8 gigahertz radiation isapplied for a duration in excess of the duration needed to fullyactivate dopant, there will be little or no adverse effect. This is incontrast to thermal activation, which simultaneously causes diffusion ofdopant. Thus, if thermal activation is conducted for an excessiveduration, there will be excessive diffusion of dopant which can lead todetrimental effects.

Another advantage of the utilization of 5.8 gigahertz radiation is thatthe effects of the radiation on dopant activation and recrystallizationare cumulative if the radiation is applied in multiple doses. Thus, asemiconductor construction may be exposed to a first dose of 5.8gigahertz radiation to partially activate dopant and/or to partiallyinduce recrystallization in a region of the construction, and then maybe later exposed to another dose of the 5.8 gigahertz radiation tocomplete the activation of the dopant and/or to complete therecrystallization. Multiple doses of microwave radiation may thus worksynergistically with one another in some embodiments, as opposed toconventional iso-thermal processes in which later doses of thermalenergy may deactivate dopants that had been activated by earlier dosesof thermal energy. This advantage of the utilization of microwaveradiation to activate dopants may be of particular utility duringfabrication of semiconductor constructions having a number of levelsstacked over one another.

As discussed in the “Background” of this disclosure, microwave radiationhas previously been utilized for both activation of dopant withinsemiconductor constructions, and for inducing crystallization ofsemiconductor materials. However, the previous utilizations of microwaveradiation did not recognize specific advantages that may be obtained byutilizing microwave radiation having a frequency of about 5.8 gigahertz.The previous utilizations of microwave radiation either utilizedradiation having a frequency other than 5.8 gigahertz; or utilized wideranges of radiation which, while including 5.8 gigahertz radiation, didnot recognize the advantage of 5.8 gigahertz radiation and treated itlike any other microwave radiation within a particular range. However,5.8 gigahertz radiation is different than at least some of the othermicrowave radiation within the prior art ranges due to thethermally-induced decoupling that occurs with 5.8 gigahertz radiation.The temperature that such thermally-induced decoupling occurs isparticularly suitable for semiconductor fabrication processes, and suchhas not been recognized or appreciated by the prior art.

Although 5.8 gigahertz radiation has thermally-induced decouplingcharacteristics particularly suitable for silicon, in some embodimentsis recognized that 5.8 gigahertz radiation may also havethermally-induced decoupling characteristics suitable for utilizationwith other semiconductor materials besides silicon.

Example embodiments in which 5.8 gigahertz radiation is utilized duringfabrication of semiconductor constructions, and/or during formation ofelectronic systems, are described with reference to FIGS. 1-17.

Referring to FIG. 1, a portion of a semiconductor construction 10 isillustrated. The semiconductor construction includes a substrate 12, anda transistor gate stack 14 formed over the substrate.

Substrate 12 may comprise semiconductor material, and in someembodiments may comprise, consist essentially of, or consist ofmonocrystalline silicon lightly doped with background p-type dopant. Theterms “semiconductive substrate” and “semiconductor substrate” mean anyconstruction comprising semiconductive material, including, but notlimited to, bulk semiconductive materials such as a semiconductive wafer(either alone or in assemblies comprising other materials thereon), andsemiconductive material layers (either alone or in assemblies comprisingother materials). The term “substrate” refers to any supportingstructure, including, but not limited to, the semiconductive substratesdescribed above.

Gate stack 14 comprises gate dielectric material 16, conductive gatematerial 18, and capping material 20.

The gate dielectric material may comprise any suitable composition orcombination of compositions, and may, for example, comprise silicondioxide.

Conductive material 18 may comprise any suitable composition orcombination of compositions, and may, for example, comprise one or moreof various metals (for instance, tungsten, titanium, etc.),metal-containing compositions (for instance, metal silicide, metalnitride, etc.), and conductively-doped semiconductor materials (forinstance, conductively-doped silicon).

Capping material 20 is electrically insulative, and may comprise anysuitable composition or combination of compositions. For instance,capping material 20 may comprise one or more of silicon dioxide, siliconnitride and silicon oxynitride.

A pair of electrically insulative sidewall spacers 22 are along theopposing sidewalls of the transistor gate stack. The sidewall spacersmay comprise any suitable composition or combination of compositions,and may, for example, comprise one or more of silicon dioxide, siliconnitride and silicon oxynitride.

Referring to FIG. 2, dopant 24 is implanted into substrate 12 to form apair of implant regions 26 on opposing sides of the transistor gatestack 14. The dopant 24 may be either n-type or p-type, and accordinglythe implant regions 26 may be either n-type doped or p-type doped. Inexample embodiments, the dopant may be selected from the groupconsisting of boron, phosphorus and arsenic. Although only one dopantimplant is illustrated, in some embodiments there may be multipleimplants of multiple types of dopants to faun various different implantregions, such as, for example, lightly-doped diffusion regions, haloregions and heavily doped regions.

The implant regions 26 may be considered to be aligned with a transistorgate comprising the gate stack 14, in that the gate stack is effectivelyutilized as a mask to define locations of the implant regions during theimplanting of dopant 24.

The implanting of dopant 24 may create defect regions (not shown) withinthe implant regions where energy from implanted dopant species interactswith monocrystalline semiconductor material (for instance,monocrystalline silicon) of substrate 12, and converts themonocrystalline material to amorphous material.

The implanted dopant at the processing stage of FIG. 2 is primarily ininterstitial positions adjacent to substitutional sites in a latticestructure of the semiconductor material of substrate 12. The dopantneeds to be activated to transfer the dopant into lattice sites of thelattice structure before the dopant will achieve a desired effect on theconductivity of the substrate within the implant regions.

Referring to FIG. 3, construction 10 is illustrated after theconstruction has been exposed to a pulse of microwave radiation having afrequency of about 5.8 gigahertz for a duration suitable to activate thedopant within implant regions 26, and to thereby convert the implantregions to electrically conductive regions (illustrated by thecross-hatching of regions 26 at the processing stage of FIG. 3). Theduration of the microwave pulse which is suitable to fully activate thedopant within implant regions 26 may be from about five minutes to about30 minutes. The pulse of microwave radiation may recrystallize amorphousdefect regions within the implant regions at the same time that thedopant is activated. Thus, the pulse of microwave radiation at about 5.8gigahertz may simultaneously heal damage regions within semiconductormaterial of substrate 12, and activate dopant.

As discussed previously, one of the advantages of utilizing microwaveradiation having a frequency of about 5.8 gigahertz is that themicrowave radiation will only couple with the silicon at temperatureswhich do not exceed about 500° C. (in some embodiments which do notexceed about 400° C., or even which do not exceed about 350° C.). Thus,the temperature of the semiconductor material of substrate 12 will notexceed about 500° C. during the exposure to the 5.8 gigahertz microwaveradiation, in some embodiments will not exceed about 400° C., and insome embodiments will not exceed about 350° C.

The sidewall spacers 22, and the materials 16 and 20 of the gate stack14 will be transparent to the microwave radiation having a frequency ofabout 5.8 gigahertz. The material 18 of the gate stack will betransparent to the radiation at 5.8 gigahertz, unless material 18comprises a conductively-doped semiconductor composition.

The substrate 12 and any conductively-doped semiconductor composition ofmaterial 18 will not heat to a temperature in excess of 500° C. throughinteraction with the microwave radiation having a frequency of about 5.8gigahertz. Thus, the temperature of substrate 12, sidewall spacers 22,and materials 16, 18 and 20 will remain at or below 500° C. (in someembodiments at or below about 400° C., and in some embodiments at orbelow about 350° C.) during the utilization of the 5.8 gigahertzmicrowave radiation for activation of dopant and/or recrystallization ofamorphous structures.

The low temperatures of the materials of construction 50 during theactivation and/or recrystallization may enable thermally-sensitivematerials to be incorporated into the construction during the exposureto the 5.8 gigahertz microwave radiation. For instance, someelectrically conductive materials that would be suitable for utilizationin the conductive gate material 18 are avoided in conventional methodsfor fabricating transistor gates, due to the thermal instability of suchmaterials under the high-temperature conditions conventionally utilizedfor activating dopant. Among such electrically conductive materials aresome metal silicides. However, the low-temperature activation(specifically, activation temperatures at or below 500° C., at or below400° C., or even at or below 350° C.) may enable such electricallyconductive materials to be utilized in the gate material 18; and thusmay enable a broader class of materials to be utilized in formingintegrated circuit components than may be utilized with conventionalprocessing. The availability of a broader class materials may enableimproved integrated circuit components to be fabricated utilizingmethods of the present invention, relative to the integrated circuitcomponents that may be fabricated utilizing conventional methods.

The transistor gate stack 14 and conductively-doped regions 26 arecomprised by a field effect transistor. There are numerous applicationsfor field effect transistors, including, for example, utilization inlogic and memory of integrated systems. FIGS. 4 and 5 illustrate amethod in which field effect transistors are incorporated into dynamicrandom access memory (DRAM), and in which 5.8 gigahertz microwaveradiation may be advantageously utilized during the formation of theDRAM.

Referring to FIG. 4, a portion of a semiconductor construction 30 isillustrated. Similar numbering will be used to describe FIG. 4 as isutilized to describe FIGS. 1-3, where appropriate.

Construction 30 comprises a semiconductor substrate 12, and a pair oftransistor gates 32 and 34 over the substrate. The transistor gatescomprise the materials 16, 18 and 20 that were discussed above.

Sidewall spacers 22 are along the opposing sidewalls of the transistorgates.

Construction 30 also comprises three implant regions 36, 38 and 40 wheredopant has been implanted into substrate 12. The implant regions may bemajority doped with either n-type dopant or p-type dopant. A firsttransistor construction comprises the transistor gate 32, and theimplant regions 36 and 38; and a second transistor constructioncomprises the transistor gate 34, and the implant regions 38 and 40.

Metal silicide (for instance, titanium silicide) 42 is formed over theimplant regions, and is utilized to electrically connect the implantregions with electrical circuitry. The metal silicide is utilized toreduce the contact resistance portion of the electrical connection toimplanted regions. Such approaches are also used to reduce the externalresistance of an associated transistor or device. Capacitors 44 and 46(schematically illustrated in the diagram of FIG. 4) are electricallyconnected to implant regions 36 and 40, respectively, through the metalsilicide; and a bitline 48 (schematically illustrated in the diagram ofFIG. 4) is electrically connected to implant region 38 through the metalsilicide.

Referring to FIG. 5, construction 30 is illustrated after microwaveradiation having a frequency of about 5.8 gigahertz is utilized toactivate dopant within implant regions 36, 38 and 40. The microwaveradiation may also be utilized to increase crystallinity of amorphousregions (not shown) within substrate 12.

One of the materials that may be particularly sensitive to thermaltemperatures in excess of 500° C. is metal silicide. Accordingly,conventional processing would activate the dopant within implant regions36, 38 and 40 prior to formation of metal silicide 42. However, theutilization of 5.8 gigahertz microwave radiation enables the activationof the dopant to be conducted after formation of metal silicide 42,without adversely affecting the metal silicide. This can improveversatility of the method utilizing 5.8 gigahertz microwave radiationfor dopant activation, relative to conventional methods. For instance,modern semiconductor fabrication often comprises formation of multiplelevels of integrated circuitry stacked over one another. It may bedesired to activate dopant across several levels simultaneously, inwhich case one or more of the levels may already have metal silicide atthe processing stage in which dopant is activated. Additionally, theremay be other applications in which it may be desired to activate dopantin an upper level after metal silicide has already been formed in alower level.

Metal silicide is one example of a material which is thermallysensitive, and which may create complications in conventional processingdue to the high activation energies that are conventionally utilized. Itmay be the low activation energy associated with transitions ofsilicides that drive using a low thermal energy process like microwave.In other words, the high thermal energy of bulk annealing may not becompatible with the low activation energy of silicide transition toundesirable state. There are numerous other thermally sensitivematerials (some of such materials may be sensitive to spike or flashtype anneals, as well as to longer anneals), and the utilization of 5.8gigahertz microwave radiation for dopant activation may enable suchmaterials to be incorporated into fabrication processes in locationswhere the materials could not be incorporated utilizing conventionaldopant activation methodologies.

FIGS. 6-9 illustrate another application where utilization of 5.8gigahertz microwave radiation for dopant activation and/orrecrystallization of semiconductor material may be advantageous, andspecifically illustrate formation of a complementary metal oxidesemiconductor (CMOS) construction.

Referring to FIG. 6, a portion of a semiconductor construction 50 isillustrated. The construction includes a substrate 12 background dopedwith p-type dopant (shown to be doped to a p−level). The substrate may,for example, comprise, consist essentially of, or consist of lightlydoped monocrystalline silicon.

An isolation region 52 extends into substrate 12. The isolation regionmay comprise, for example, a shallow trench isolation region.Accordingly, the isolation region may comprise a trench formed withinsubstrate 12 and filled with one or more insulative materials; with anexample insulative material suitable for utilization in the trenchedisolation region being silicon dioxide.

A patterned masking material 54 is over substrate 12. Material 54 may,for example, comprise photolithographically patterned photoresist. Thematerial 54 blocks one portion of the substrate, while leaving anotherportion exposed.

Referring to FIG. 7, n-type dopant is implanted into the exposed portionof substrate 12 to form an n-well 56. The n-well is shown to be doped toan n−level.

Referring to FIG. 8, masking material 54 (FIG. 7) is removed, and a pairof complementary transistors 58 and 60 are formed over substrate 12.Transistor 58 is a p-channel device, and transistor 60 is an n-channeldevice.

Transistor 58 includes a transistor gate comprising gate dielectricmaterial 62, conductive gate material 64, and capping material 66.Transistor 58 further includes a pair of sidewall spacers 74, and a pairof implant regions 76.

Transistor 60 includes a transistor gate comprising gate dielectricmaterial 68, conductive gate material 70 and capping material 72.Additionally, transistor 60 includes a pair of sidewall spacers 78, anda pair of implant regions 80.

The implant regions 76 will be majority p-type doped, while the implantregions 80 will be majority n-type doped. In some embodiments, theformation of the n well may be considered to comprise implanting a firstdopant having a first conductivity type (with such first dopant havingan n-type conductivity type in the shown embodiment); and the formationof the implant regions 76 may be considered to comprise implanting ofsecond dopant having a second conductivity type opposite to the firstconductivity type. In the shown embodiment, the implanting of the seconddopant forms implant regions entirely contained within the implantregion formed by the implanting of the first dopant (in other words, thep-type implant regions 76 are entirely contained within the n-well 56).

Referring to FIG. 9, the dopants within implant regions 76 and 80 areactivated, and accordingly the implant regions become conductively-dopedsource/drain regions. The activation of the dopants within implantregions 76 and 80 utilizes microwave radiation having a frequency ofabout 5.8 gigahertz, and may simultaneously repair anychanged-crystallinity damage regions that occurred within substrate 12during formation of the implant regions.

The activation of the dopants within implant regions 76 and 80 may occursimultaneously with activation of the background n-type dopant of then-well, and the activation of the background p-type dopant withinsubstrate 12 adjacent the n-well. Alternatively, the background n-typeand p-type dopants may be at least partially activated prior toactivation of the dopants within the implant regions 76 and 80. If thebackground n-type and p-type dopants are fully activated prior toformation of implant regions 76 and 80, such activation may utilizeconventional methods or may utilize 5.8 gigahertz microwave radiation.If the background n-type and p-type dopants are only partially activatedprior to formation of implant regions 76 and 80, such partial activationmay comprise utilization of 5.8 gigahertz microwave radiation; and theactivation of the background n-type and p-type dopants may be completedduring the subsequent utilization of 5.8 gigahertz microwave radiationto activate the dopant within the implant regions 76 and 80.

The utilization of 5.8 gigahertz microwave radiation for activation ofthe dopants within implant regions 76 and 80 may enablethermally-sensitive materials to be utilized in forming the CMOSconstruction. Also, although the activation of the dopants withinimplant regions 76 and 80 is shown occurring prior to formation of othermaterials and structures over the implant regions 76 and 80, in otherembodiments (not shown) one or more thermally-sensitive materials (forinstance, metal silicide) may be formed over the implant regions priorto the activation of dopant within such implant regions.

The advantages of utilization of 5.8 gigahertz microwave radiation foractivation of dopant and/or crystallization of semiconductor materialsextend to numerous electrical components besides the transistorsdiscussed above. For instance, semiconductor device fabricationfrequently comprises formation of an n-type doped region directlyagainst a p-type doped region to form a diode. If dopants diffuse fromthe n-type regions and p-type regions across the boundary between then-type and p-type regions, the interface between the n-type and p-typeregions becomes blurred, and the performance of the diode may beadversely affected. An advantage of the utilization of 5.8 gigahertzmicrowave radiation for dopant activation during fabrication of a diodeis that the low-temperature of the dopant activation will substantiallyreduce thermally-induced diffusion of dopant relative to conventionalmethods. Thus, there may be little, if any, diffusion of dopant across ap-n interface if 5.8 gigahertz microwave radiation is used foractivation of the dopant of a p-n diode.

FIGS. 10 and 11 illustrate an example method of forming a diode. FIG. 10shows a portion of a semiconductor construction 90. Such constructioncomprises a semiconductor material 92 (for instance, monocrystallinesilicon) having a region 94 heavily doped with n-type dopant (showndoped to an n+ level), and having a region 96 heavily doped with p-typedopant (shown doped to a p+ level). The regions 94 and 96 are shown tobe directly against each other, with an interface 95 being illustratedas a line between the regions 94 and 96. Although p+ and n+ levels areillustrated, in some embodiments various combinations of p, p+, p−, n,n+ and n− levels may be utilized (with p− and n− levels being less thanor equal to about 10¹⁸ atoms/cm³, and with p+ and n+ levels beinggreater than or equal to about 10²² atoms/cm³).

The regions 94 and 96 may be formed by implanting n-type dopant andp-type dopant into material 92. For instance a first mask (not shown)may be utilized to block one of the regions 94 and 96 while dopant isimplanted into the other of the regions. The first mask may then beremoved and replaced with a second mask (not shown) which blockswhichever of the regions 94 and 96 has received the implant, whiledopant is implanted into the other of the regions. The second mask maythen be removed to leave the construction of FIG. 10.

Referring to FIG. 11, the n-type dopant of region 94 and the p-typedopant of region 96 are activated by exposure to 5.8 gigahertz microwaveradiation, with such activation being diagrammatically illustrated withcrosshatching of regions 94 and 96.

The activation has led to modest diffusion of dopant across interface95, with such diffusion being diagrammatically illustrated bydashed-line boundaries 97. In some embodiments there may be effectivelyno diffusion across the interface 95. Regardless of whether there is nodiffusion, or modest diffusion, the utilization of 5.8 gigahertzmicrowave radiation may enable a p-n diode to be formed with a muchsharper interface between the p-type doped region and the n-type dopedregion than is formed by conventional methods. Thus, utilization of 5.8gigahertz microwave radiation for activation of the dopants of a p-ndiode may lead to fabrication of a p-n diode having improved performancecharacteristics relative to p-n diodes formed by conventional methods.

Another advantage of the utilization of 5.8 gigahertz microwaveradiation for the activation of dopants of a p-n diode is that such mayenable the activation to be conducted after thermally-sensitivematerials have been formed proximate the diode. FIG. 12 illustrates aportion of a semiconductor construction 100 in accordance with anexample embodiment in which thermally-sensitive materials are formedproximate a p-n diode.

The semiconductor construction 100 includes a semiconductor substrate102 supporting a pair of memory cells 104 and 106.

Substrate 102 may comprise monocrystalline silicon and one or morematerials (not shown) of an integrated circuit construction. Suchmaterials may include electrically conductive materials, electricallyinsulative materials and/or semiconductive materials.

Memory cell 104 comprises phase change material 108 between a pair ofelectrically conductive electrodes 110 and 112 (the electrode 110 wouldbe out of the plane of the cross-section of FIG. 12, and thus is shownin dashed-line, or phantom, view). The electrodes may be connected toother circuitry (not shown) which is out of the plane of thecross-section of FIG. 12. The electrodes may comprise any suitableelectrically conductive composition, or combination of electricallyconductive compositions, and may, for example, comprise, consistessentially of, or consist of conductively-doped semiconductor material,various metals, and/or various metal-containing compositions.

Phase change material 108 may comprise any suitable composition orcombination of compositions, and in some embodiments may comprise,consist essentially of, or consist of GST (i.e., a mixture of germanium,antimony and tellurium).

The electrodes 110 and 112 are utilized for altering phase changematerial 108 during the storage of information in the memory cell 104,as well as for determining the state of phase change material 108 duringthe reading of information from the memory cell 104.

Memory cell 106 comprises phase change material 114 between a pair ofelectrically conductive electrodes 116 and 118 (the electrode 118 wouldbe out of the plane of the cross-section of FIG. 12, and thus is shownin dashed-line, or phantom, view). The electrodes may be connected toother circuitry (not shown) which is out of the plane of thecross-section of FIG. 12. The electrodes 116 and 118 may comprise any ofthe compositions discussed above regarding electrodes 110 and 112.

Phase change material 114 may comprise any suitable composition orcombination of compositions, and in some embodiments may comprise,consist essentially of, or consist of GST.

The electrodes 116 and 118 are utilized during the storage ofinformation in the memory cell 106, and during the reading ofinformation from the memory cell, analogously to the utilization ofelectrodes 110 and 112 in the reading and writing relative to memorycell 104.

The phase change materials 108 and 114 may be referred to as first andsecond phase change materials in some embodiments.

A pair of diodes 120 and 140 are provided between the memory cells 104and 106. The diode 120 comprises a semiconductor material 122, and thediode 140 comprises a semiconductor material 142. A bitline 150 isbetween the diodes 120 and 140. The bitline 150 is a common bitlinerelative to memory cells 104 and 106.

The construction 100 may be formed by forming semiconductor material 122over electrode 112 of memory cell 104, forming the bitline 150 oversemiconductor material 122, forming semiconductor material 142 over thebitline, and then forming the electrode 116 of memory cell 106 over thesemiconductor material 142.

Semiconductor materials 122 and 142 may comprise any suitablecomposition or combination of compositions, and may be the samecomposition as one another or may differ from one another incomposition. In some embodiments, semiconductor materials 122 and 142may comprise, consist essentially of, or consist of monocrystallinesilicon.

The semiconductor material 122 comprises a doped region 124, and anotherdoped region 126 directly against the doped region 124; and thesemiconductor material 142 comprises a doped region 144, and anotherdoped region 146 directly against the doped region 144.

One of the doped regions 122 and 124 may be referred to as a first dopedregion, and is majority p-type doped; and the other of the doped regionsmay be referred to as a second doped region, and is majority n-typedoped. In subsequent processing, the doped regions 124 and 126 may beexposed to microwave radiation having a frequency of about 5.8 gigahertzto activate dopant within such doped regions (analogously to theactivation discussed above with reference to FIGS. 10 and 11).Analogously, one of the doped regions 142 and 144 may be referred to asa first doped region, and is majority p-type doped; and the other of thedoped regions may be referred to as a second doped region, and ismajority n-type doped. In subsequent processing, the doped regions 144and 146 may be exposed to microwave radiation having a frequency ofabout 5.8 gigahertz to activate dopant within such doped regions.

The phase change materials 108 and 114 may be considered to be fowledproximate semiconductor materials 122 and 142. The utilization of the5.8 gigahertz microwave radiation advantageously occurs with low thermalimpact on the nearby phase change materials (specifically, is at atemperature at or below 500° C., at or below 400° C., or even at orbelow 350° C.), and accordingly may be conducted without detriment tothe phase change materials. In contrast, it is difficult to form a p-ndiode proximate phase change materials utilizing conventional processingbecause the phase change materials tend to be highly thermallysensitive. Accordingly, the thermal impact of conventional dopantactivation methods tend to detrimentally affect the phase changematerials.

The construction 100 comprises semiconductor materials 122 and 142formed after the first phase change material 108, and prior to thesecond phase change material 114. Accordingly, the activation of dopantwithin regions 124, 126, 144 and 146 will occur after formation of thefirst phase change material 108, but may occur before or after formationof the second phase change material 114.

Construction 100 is shown comprising electrically insulative material130 along the memory cells 104 and 106, along the bitline 150, and alongthe diodes 120 and 140. Insulative material 130 may comprise anysuitable composition, or combination of compositions, and in someembodiments may comprise one or both of silicon dioxide and siliconnitride.

The phase change materials 108 and 114 are examples of thermallysensitive memory element materials that may be utilized in the memorycells 104 and 106. Other thermally sensitive memory element materialsmay be utilized in other embodiments, with such other memory elementmaterials including, for example, electrically resistive materials.

As discussed above, the effects of 5.8 gigahertz microwave radiation arecumulative so that a doped region may be activated with severalsequential pulses of microwave radiation and/or an amorphous regioncrystallized with several sequential pulses of microwave radiation. Yet,the effects of exposure to 5.8 gigahertz microwave radiation are alsoself-limiting so that excessive exposure to the 5.8 gigahertz microwaveradiation will not create adverse effects. These properties of 5.8gigahertz microwave radiation may be taken advantage of duringfabrication of multiple levels of integrated circuitry over asemiconductor substrate, such as, for example, during fabrication ofthree-dimensional stacked memory.

FIG. 13 shows a semiconductor construction 200 comprising asemiconductor substrate 202, and a plurality of integrated circuitlevels 204, 206, 208, 210, 212, and 214 formed over the semiconductorsubstrate. Each level may comprise numerous semiconductor components(for instance, volatile cells, non-volatile cells, wiring, capacitors,etc.). The components may comprise electrically conductive materials.Example electrically conductive materials are diagrammaticallyillustrated as materials 216, 218, 220 and 222.

Boundaries between the various levels of integrated circuitry arediagrammatically illustrated with dashed lines 205, 207, 209, 211, and213; and an upper surface of the substrate is diagrammaticallyillustrated with a solid line 203.

Numerous doped regions are formed at various levels within construction200, with example doped regions being diagrammatically illustrated asregions 230, 232, 234, 236, 238, 240, 242, 244, 246, 248, 250 and 252.The doped regions may be utilized for numerous purposes. For instance,the large doped region 230 within substrate 202 may be a getteringregion, whereas others of the doped regions may ultimately be utilizedas a source/drain regions, portions of diodes, portions of conductivewiring, etc.

Several of the various doped regions will be formed at differentprocessing stages relative to one other, with the doped regions in thelower levels generally being formed before the doped regions at thehigher levels.

In some embodiments, a doped region at a lower level (for instance, oneof the regions 230, 232, 234, 236 and 238) may be referred to as a firstdoped region, and a doped region at a higher level (for instance, one ofthe regions 250 and 252) may be referred to as a second doped region. Afirst pulse of microwave radiation having a frequency of about 5.8gigahertz may be utilized to activate the dopant within the first dopedregion. In some embodiments, the first pulse may be conducted for aduration suitable to activate some, but not all of the dopant within thefirst doped region. Subsequently, the second doped region may be formed,and then a second pulse of microwave radiation having the frequency ofabout 5.8 gigahertz may be utilized to complete activation of the dopantwithin the first doped region while also activating all of the dopantwithin the second doped region.

Construction 200 may comprise one or more materials that are thermallysensitive, and specifically which are adversely affected by temperaturesin excess of 500° C. Such materials may include, for example, phasechange materials and/or metal silicides. One or more of the pulses ofmicrowave radiation may be utilized after such materials have beenincorporated into construction 200, since the 5.8 gigahertz microwaveradiation can be used without heating the semiconductor construction toa temperature exceeding 500° C. In some embodiments, the thermallysensitive materials may be adversely affected by temperatures in excessof 400° C., or even in excess of 350° C., and the treatment with themicrowave radiation having a frequency of 5.8 gigahertz may be utilizedwithout adversely impacting such materials.

Although many of the embodiments discussed above indicate that microwaveradiation having a frequency of 5.8 gigahertz may be utilized tosimultaneously activate dopant and increase crystallization within asemiconductor substrate, there may be embodiments in which it is desiredto activate dopant without substantially increasing crystallization orvice versa. In such embodiments, the duration of the pulse of microwaveradiation may be adjusted in an attempt to accomplish primarily one orthe other of dopant activation and crystallization.

Although the example embodiments of FIGS. 1-13 are directed towardfabrication of integrated circuitry, the utilization of 5.8 gigahertzmicrowave radiation may be applied to other semiconductor fabricationprocesses in other embodiments, including, for example, fabrication ofMEMS.

The structures formed by the methods of FIGS. 1-13 may be incorporatedinto various electronic systems. FIGS. 14-17 illustrate exampleelectronic systems that may utilize one or more of such structures.

FIG. 14 illustrates an embodiment of a computer system 400. Computersystem 400 includes a monitor 401 or other communication output device,a keyboard 402 or other communication input device, and a motherboard404. Motherboard 404 may carry a microprocessor 406 or other dataprocessing unit, and at least one memory device 408. Memory device 408may comprise an array of memory cells, and such array may be coupledwith addressing circuitry for accessing individual memory cells in thearray. Further, the memory cell array may be coupled to a read circuitfor reading data from the memory cells. The addressing and readcircuitry may be utilized for conveying information between memorydevice 408 and processor 406. Such is illustrated in the block diagramof the motherboard 404 shown in FIG. 15. In such block diagram, theaddressing circuitry is illustrated as 410 and the read circuitry isillustrated as 412.

Processor device 406 may correspond to a processor module, andassociated memory utilized with the module may comprise one or morestructures formed by the methods of FIGS. 1-13.

Memory device 408 may correspond to a memory module, and may compriseone or more structures formed by the methods of FIGS. 1-13.

FIG. 16 illustrates a simplified block diagram of a high-levelorganization of an electronic system 700. System 700 may correspond to,for example, a computer system, a process control system, or any othersystem that employs a processor and associated memory. Electronic system700 has functional elements, including a processor 702, a control unit704, a memory device unit 706 and an input/output (I/O) device 708 (itis to be understood that the system may have a plurality of processors,control units, memory device units and/or I/O devices in variousembodiments). Generally, electronic system 700 will have a native set ofinstructions that specify operations to be performed on data by theprocessor 702 and other interactions between the processor 702, thememory device unit 706 and the I/O device 708. The control unit 704coordinates all operations of the processor 702, the memory device 706and the I/O device 708 by continuously cycling through a set ofoperations that cause instructions to be fetched from the memory device706 and executed. The memory device 706 may include one or morestructures formed by the methods of FIGS. 1-13.

FIG. 17 is a simplified block diagram of an electronic system 800. Thesystem 800 includes a memory device 802 that has an array of memorycells 804, address decoder 806, row access circuitry 808, column accesscircuitry 810, read/write control circuitry 812 for controllingoperations, and input/output circuitry 814. The memory device 802further includes power circuitry 816, and sensors 820, such as currentsensors for determining whether a memory cell is in a low-thresholdconducting state or in a high-threshold non-conducting state. Theillustrated power circuitry 816 includes power supply circuitry 880,circuitry 882 for providing a reference voltage, an interconnection line884 for providing a first wordline with pulses, an interconnection line886 for providing a second wordline with pulses, and an interconnectionline 888 for providing a bitline with pulses. The system 800 alsoincludes a processor 822, or memory controller for memory accessing.

The memory device 802 receives control signals from the processor 822over wiring or metallization lines. The memory device 802 is used tostore data which is accessed via I/O lines. At least one of theprocessor 822 and memory device 802 may include one or more structuresformed by the methods of FIGS. 1-13.

The various electronic systems may be fabricated in single-packageprocessing units, or even on a single semiconductor chip, in order toreduce the communication time between the processor and the memorydevice(s).

The electronic systems may be used in memory modules, device drivers,power modules, communication modems, processor modules, andapplication-specific modules, and may include multilayer, multichipmodules.

The electronic systems may be any of a broad range of systems, such asclocks, televisions, cell phones, personal computers, automobiles,industrial control systems, aircraft, etc.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

1. A method of forming a semiconductor construction, comprising: implanting dopant into semiconductor material, the implanting forming damage regions within the semiconductor material; and simultaneously activating the dopant and repairing the damage regions by exposing the semiconductor material to microwave radiation having a main spectrum wavelength peak at about 5.2 centimeters, a temperature of the semiconductor material not exceeding about 500° C. during the exposure to the microwave radiation.
 2. The method of claim 1 wherein the temperature does not exceed about 350° C.
 3. The method of claim 1 wherein the dopant comprises one or more of boron, phosphorus and arsenic.
 4. The method of claim 1 wherein: the implanting is a first implanting and comprises implanting of a first dopant having a first conductivity type; a second implanting is conducted after the first implanting, and the second implanting comprises implanting of a second dopant having a second conductivity type that is opposite to the first conductivity type; and the activation of the dopant and the repair of the damage regions occurs after the first and second implantings.
 5. The method of claim 4 wherein the first and second implantings form a p-type region of the semiconductor material directly against an n-type region of the semiconductor material, and wherein the p-type region and the n-type region are together comprised by a p-n diode.
 6. The method of claim 1 further comprising forming a transistor gate over the semiconductor material prior to implanting the dopant, and wherein the implanting forms conductively-doped source/drain regions aligned with the gate.
 7. The method of claim 6 further comprising forming metal silicide over and directly against the conductively-doped source/drain regions prior to the activation of the dopant.
 8. A method of forming integrated circuitry, comprising: providing first dopant within semiconductor material of a semiconductor construction; utilizing a first pulse of microwave radiation having a frequency of about 5.8 gigahertz for a duration suitable to activate only some of the first dopant, while a temperature of the semiconductor material remains at less than or equal to about 500° C.; after utilizing the first pulse of microwave radiation; providing second dopant within the semiconductor material; and utilizing a second pulse of microwave radiation having a frequency of about 5.8 gigahertz for a duration suitable to complete activation of the first dopant and to fully activate the second dopant, while a temperature of the semiconductor material remains at less than or equal to about 500° C.
 9. The method of claim 8 wherein: the temperature during the first pulse of microwave radiation remains at less than or equal to about 400° C.; and the temperature during the second pulse of microwave radiation remains at less than or equal to about 400° C.
 10. The method of claim 8 wherein: the temperature during the first pulse of microwave radiation remains at less than or equal to about 350° C.; and the temperature during the second pulse of microwave radiation remains at less than or equal to about 350° C.
 11. The method of claim 8 wherein: the semiconductor construction is formed to include phase change material; and the second pulse of radiation is utilized after the phase change material is incorporated into the semiconductor construction.
 12. The method of claim 8 wherein: the semiconductor construction is formed to include metal silicide; and the second pulse of radiation is utilized after the metal silicide is incorporated into the semiconductor construction.
 13. A method of forming integrated circuitry, comprising the following steps in the listed order: providing dopant within a semiconductor material; utilizing a first pulse of microwave radiation having a frequency of about 5.8 gigahertz for a duration suitable to activate only some of the dopant, while a temperature of the semiconductor material remains at less than or equal to about 500° C.; forming one or more additional materials over the semiconductor material; and utilizing a second pulse of microwave radiation having a frequency of about 5.8 gigahertz for a duration suitable to complete activation of the dopant, while a temperature of the semiconductor material remains at less than or equal to about 500° C.
 14. The method of claim 13 wherein: the temperature during the first pulse of microwave radiation remains at less than or equal to about 400° C.; and the temperature during the second pulse of microwave radiation remains at less than or equal to about 400° C.
 15. The method of claim 13 wherein: the temperature during the first pulse of microwave radiation remains at less than or equal to about 350° C.; and the temperature during the second pulse of microwave radiation remains at less than or equal to about 350° C.
 16. The method of claim 13 further comprising incorporating the dopant into a volatile memory cell.
 17. The method of claim 13 further comprising incorporating the dopant into a non-volatile memory cell.
 18. The method of claim 13 further comprising incorporating the dopant into a diode. 